Diagnosis
The control panel itself has likely failed or become disconnected. The main board is sending power (hence the fan), but the LCD isn't getting a signal.
How to Fix It
Unplug the printer for 5 minutes. Plug it back in. If the screen stays dead, it needs a new control panel assembly. This involves removing the top cover of the printer to access the connector. For most people, this is a service call.
If That Didn't Work
Before you conclude it's hardware, try a full reset. With the printer off, hold down the 'Go' button and power it on. Keep holding 'Go' until the drum LEDs cycle, then release. This performs a factory network reset and can sometimes wake a stuck panel.
Heads Up
If you're getting prints via network even with a dead screen, the printer is otherwise functional. You just can't change any settings locally. A repair might cost enough that it's worth considering a replacement if the printer is older.